Validation of an ex vivo dental pulp infection model and its responses to triclosan exposure. M.M NATARAJAN¹, W. NISHIO AYRE¹,J. MAILLARD², C.D. LYNCH¹ and A. SLOAN¹ . Tissue Engineering and Reparative Dentistry and Pharmacy & Pharmaceutical Sciences, Cardiff University, Cardiff, Wales.

Objectives: Objective: Previously, we have developed an ex vivo dental pulp infection model, however it was not fully validated for therapeutic intervention. Therefore the aim of this study was to (I) validate this model and (II) evaluate its histological and inflammatory response to an antimicrobial agent, triclosan.
Methods: Methods: Transverse tooth slices (2mm) were prepared from rat incisors and cultured in Dulbecco’s Eagles Media (DMEM) for 24h. Then the tooth sections ± triclosan (12μg/mL) treatment were inoculated with fluorescein diacetate stained Streptococcus anginosus Group (SAG) bacteria in DMEM + 10% Brain Heart Infusion media and incubated for 24h. Furthermore, triclosan pre-treated pulp tissues were included to find its impact on area of colonisation. The samples were harvested at 0, 6, 12 or 24h for further analysis. Tissue damage was assessed by histological analysis. Expression of cytokines was assessed by qRT-PCR technique.
Results: Results: A significant (p<0.001 & p<0.01) reduction in dental pulp cells and odontoblast count was found with infected tooth slices from 12h and 24h respectively. The percentage area of SAG colonisation increased between 6-24h (p<0.01). The pro-inflammatory markers IL-1β, TNF-α, IL-18 were significantly (p<0.01) upregulated by SAG infection. Conversely, anti-inflammatory marker IL-10 was found to be significantly down regulated. Triclosan treatment significantly reduced the SAG area of colonisation in a time depended manner. Triclosan reduced the IL-1β, TNF-α, IL-18 expression and maintained IL-10 levels.
Conclusions: Conclusion: The ex vivo model showed similar inflammatory responses to human pulpal infections as described in the litrature. Triclosan offers the potential as an antimicrobial and anti-inflammatory agent for endodontic treatment.